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The instructions say "at least 4L or 1 Gallon containers" BUT the container shown in all the photos is an ordinary plastic drinking glass, significantly less than 1 liter. The directions also say to glue the toe of a black sock to the inside bottom of the container, then call for stretching the sock over the rim of the container, all the way down the outside and gluing the top of the sock around the bottom outside of the container. Perhaps if your local stores carry socks for elephants, this might work on a 4L or 1 Gallon container, but socks for people (even size XL) are simply not going to stretch that well (they will stretch fine for the tiny container shown in the photos).
There is no need for the 6.5" elements, unless you have a UHF SWR meter and want to spend a lot of time installing the antenna, measuring SWR, taking it down, trimming the elements, re-installing the antenna, measuring SWR, taking it back down, trimming the elements again, etc., etc. until you get it set for one precise frequency. The common version of this antenna uses all 19.5" elements -- ONE up and four down -- is easier to build, gives dual band performance at least as good as this more complicated version, and a significantly smoother omnidirectional radiation pattern.Hams should know that a quarter-wave element for 2m VHF will also work as a three-quarter-wave element on 70cm UHF.